The present invention relates to semiconductor devices, and in particular, to metal contacts to III-V semiconductor material.
A metal-semiconductor contact has a potential barrier, namely a Schottky barrier, which can be modified by appropriate doping, etc. so that this contact may be either a rectifying contact or a resistive contact depending on the application in an integrated circuit. Thus modification of the Schottky barrier is of concern.
For example, U.S. Pat. No. 4,394,673 which is incorporated by reference discloses providing silicide contacts on a silicon substrate wherein the barriers are either greater than 0.8 eV or lower than 0.4 eV. Rare earths are deposited as thin films on silicon and heated there to form the silicide layer.
In another example, U.S. Pat. No. 4,796,082 which is incorporated by reference makes a low resistive contact on a GaAs substrate when indium diffuses into the gallium arsenide substrate to form a uniform layer of InGaAs. A layer of nickel is initially interposed between the indium and the substrate.
Although the above satisfy the noted objectives, one would like to be able to tailor the Schottky barrier height for a maximum value independent of the contact metal.